Slit lamp apparatus which have a peripheral illuminating device in addition to the slit illuminating device are known as so-called photo-slit lamps and are described in the paper "Augenuntersuchung mit der Spaltlampe" published by Carl Zeiss, Oberkochen. With these known photo-slit lamps, it is disadvantageous that the incidence angle of the peripheral illuminating device can only be changed when this illuminating device is pivoted together with the stereomicroscope about the rotational axis of the apparatus mechanism about which the slit illuminating device is also pivotable.
The plane of the slit image and the microscope focal plane contain the virtual extension line of this rotational axis. By means of an instrument base, this plane can be displaced in X, Y, Z direction at the location of the examination in the eye. The mechanical support of this common rotational axis for the slit illuminating device and for the stereomicroscope can be arranged above or below the head of the patient in accordance with the configuration of the slit lamp device.